Recently, in dialysis apparatus, such as a blood purification apparatus, a technique has been suggested that performs priming, reinfusion, and dialysate infusion (emergency dialysate infusion) using a dialysate supplied to a dialyzer during dialysis treatment (particularly, an on-line HDF or an on-line HF). Japanese Laid-open Patent Publication No. 2004-313522 discloses a dialysis apparatus that includes a dialysate infusing line. One end is connected to a collection port formed in a predetermined part of a dialysate introduction line. The other end is connected to a blood circuit (arterial blood circuit or venous blood circuit), with a dialysate infusing pump disposed in the dialysate infusing line. In order to perform priming, the reinfusion or the dialysate infusion, the emergency dialysate infusion, using the dialysis apparatus, the dialysate in a dialysate introduction line is supplied to the blood circuit, arterial blood circuit or venous blood circuit, by driving the dialysate infusing pump.